Conventional riflescopes or telescopic sights include windage and elevation adjustments to enable initial "zeroing in" of the sight, and to permit adjustment of the sight for accurate shooting in cross-wind conditions and at different target distances. These adjustments are made by shifting the position of an internal sighting reticle (typically of a crosshair style), or preferably by optically shifting the position of the target image with respect to an always-centered reticle. The latter kind of adjustment is usually made by shifting the position of an internal tubular cell which carries erector lenses used in the riflescope optical system.
Most riflescope elevation or range adjustments include a rotatable dial graduated in minutes of angle, and adjustable only after removal of a protective cover or cap with the rifle held in a non-firing position. An improved adjustment system displays range directly in terms of target distance, and interchangeable yardage scales may be provided to compensate for the trajectories of various rifles and ammunitions. Examples of such improved systems are disclosed in U.S. Pat. Nos. 2,105,564, 2,583,042, 3,484,148 and 3,826,012.
The elevation adjustment of this invention provides a direct-reading distance scale which is enclosed in a housing to be sheltered from weather and impact damage, and which is easily viewed and adjusted while the rifle is held in a normal firing position. Adjustment of the elevation setting does not require tools or removal of parts, and the assembly is provided with a click-stop feature to enable rapid conventional elevation settings to be made if the yardage scale is not used. Different range scales can be used interchangeably in the assembly, and both installation and zeroing of a particular scale is easily achieved without extensive disassembly or use of special tools.